Monday, November 28, 2011

Making transportation more sustainable at the operations level has certain benefits. However, usually operations-level improvements are targeted at making vehicle traffic more efficient - reducing delay and congestion and improving travel times. It can be argued that an operations approach to sustainability is only treating the symptoms, but not the cause. Causal strategies to effect mode choice, shorten trips, or eliminate vehicle trips altogether requires solutions that address land use and development. There are a number of strategies and tools that are available to planners and designers to improve transportation sustainability at the development level. This presentation will look at these tools and categorize the good, better and best practices.

Wednesday, November 23, 2011

The City of Portland installed a dynamic warning sign at NE Grand and Couch in Portland during the past week. The intent was to clarify the traffic control at the intersection and to warn motorists of an approaching cyclist.

Inductive loop detection is located upstream from the traffic signal by 200 feet. We have second detector in the bike lane approximately 60 feet downstream is used to identify and confirm that all people on bicycles are approaching the signal.

The active sign is behind the no turn on red sign and the advance ctop here on red sign.

50' from the intersection you can see the bike box and the active warning sign. The arrow in the bike lane advances.

A close up of the sign shows the information. This is the same message as the MUTCD sign with the exception of the bike lane and the bicycle (the MUTCD sign is only for pedestrians). The sign is the same size as the signal head (3' x 3')

I got a call today from a colleague who was working for Vancouver BC. They were doing research on safety of pedestrian and bicycle travel and one of the things that BC has experienced is a higher crash rate of pedestrians and left turns than cities such as Portland.There other peer cities were Toronto, Calgary, Seattle, and San Francisco.

The answer to this was easy for me. Downtown Vancouver BC has quite a few two way streets (one is shown in the picture to the left) which results in permissive operations. When operating a motor vehicle and navigating across two lanes of approaching traffic and pedestrians from both directions on the crossings it is difficult to gauge the relative safety of accepting a gap. This is also confounded when we throw people on bicycles into this where vehicles may not see the oncoming person (low light visibility, etc).

Which brings me back to a post I had on twitter awhile back, with some research that supported this perspective. It read as follows:

The research suggests increasing the yellow and all red times at the intersections (not a good idea in my opinion), but also states the following:

Speciﬁcally, the analysis indicated a statistically signiﬁcant reduction (at the 0.05 level) in 34 total crashes as a result of (1) increasing the all red phase only and (2) increasing the total change interval to be less than the ITE recommended practice. Injury crashes were signiﬁcantly reduced as a result of increasing the total change interval to be less than the ITE recommendedpractice. Rear-end crashes were signiﬁcantly reduced as a result of increasing the total change interval to be greater than the ITE recommended practice. The change in angle crashes was statistically insigniﬁcant under all scenarios investigated.Table 6.3 also has the caveat that " The sample of sites used in this evaluation is limited. So these results should be used with due caution."

Friday, November 18, 2011

Great couple of posts on Traffic Signals, yet the perspecptives on signal timing are about more than 10 years old from the Portland viewpoint. We've had transit priority since 1999 and the signals never leave coordination. LRT preemption isn't terribly novel and the staff in Portland are continuing to work with our software vendors on ways to make it more effective.

The article that inspired this are here:Fighting Congestion in Minneapolis on a Tight Budget
It's not about fighting congestion, it's about taking a look at the policy and determining the best solution given the desired outcomes. Do you want people to take bus, should transit be a competitive mode, if so, manage congestion, don't fight it is a philosophy that has been employed in Portland.

Yes, Downtown Portland is the perfect example of this, we progress traffic in one direction on our one way street grid and pedestrians in the opposite direction. Does everyone know this? No, but at least we're trying to make it so that half of the time when you're walking downtown you're delayed less than you would be otherwise. We also limit delays to pedestrians by keeping the cycle lengths low, which with short blocks (260' in downtown) is important to reduce the amount of gridlock (traffic queues spilling back between intersections) that occurs during the peak traffic hours. Portland doesn't accomplish this during the typical weekday, but that is life in the big city.

Bicycle scale traffic signal indications have been implemented in Portland. We purchased 4" signal heads from Gesig, a company in Austria that we were able to contact and make arrangements to procure the equipment. That was a significant obstacle because of the small quantity order, the lack of a local distributor, and the Euro-US financial transaction (IRS forms, etc).

The supplemental 4" signal head will be placed on the nearside pole shown above (there is also some ornamental canopy treatments on the pole) to provide a nearside installation that is consistent with the scale that a person on the bicycle needs to get an indication that doesn't blind them with the brightness of an automobile signal. The nearside indication is simply a supplemental head, supporting the 8" indication that is farside of the intersection. The initial installation shown in this picture (this was taken before the signal was turned on) shows 12" heads that are standard, but the contractor and the distributor of the equipment they were working with failed to read the plans correctly.

BikePortland.org author Jonathon Maus has a really nice video on opening day. If you watch the video, this was developed prior to the turnon of the signal at SW Moody and Gibbs.

We modified a signal to the north of this location at SW Sheridan and SW Moody and added a diagonal bicycle crossing complete with green striping that indicates that the crossing is for bicycles in a diagonal direction. I especially like in the video at 2:20 the flagger conversation.